Synthetic lubricant



United States Patent 2,894,909 SYNTHETIC LUBRICANT Charles E. Saunders,Silver Spring, Md., assignor to United States of America as representedby the Secretary of the Navy No Drawing. Application August 9, 1956Serial No. 603,196

3 Claims. (Cl. 252-345) (Granted under Title 35, US. Code (1952), sec.266) The invention described herein may be manufactured and used by orfor the Government of the United States of America for governmentalpurposes without the payment of any royalties thereon or therefor.

The present invention relates to synthetic lubricants and additivestherefor. More particularly the invention relates to water solublepolymerized alkylene oxide oils and to additives which improve thelubricity and antioxidant characteristics of these oils so as to makethem useful under extreme ambient conditions while retaining their watersoluble characteristics.

This application is a continuation-in-part of Serial No. 241,379, filedAugust 10, 1951, now abandoned.

Improved high powered turbine type internal combustion engines haverecently been developed for use in high speed underwater ordnanceequipment such as submarines and torpedoes. An example of this type ofengine is the hydrogen peroxide propelled engine used in submarines.This engine is combined with the conventional diesel engine with theperoxide reserved for special bursts of speed in attacking and escaping.Free oxygen combines with fuel such as diesel oil to produce the steamand carbon dioxide to drive the turbine under ordinary conditions. Whenhigh speed is desired the hydrogen peroxide is utilized as the fuel. Thehydrogen peroxide breaks down to provide the heat used as the source ofenergy. The principal advantage of the use of hydrogen peroxide is thatno exhaust bubbles reach the surface thus adding a safety factor to thesubmarines operation. The hydrogen peroxide engine, however, developstemperatures in the nature of 1200 degrees F. so that it is highlydesirable to utilize sea water as a coolant. This sea water coolanttends to wash away the lubricants employed in the engine and suchlubricants are discharged with the sea Water. Ordinary lubricants beinginsoluble in sea water tend to form a wake in the form of an oil slickwhich rises to the surface. The presence of this slick may be detectedby surface craft and the advantage the submarine has obtained throughthe use of the hydrogen peroxide engine is largely overcome. In additionordinary lubricants tend to wash off the engine parts in the presence ofsea water. They also are extremely corrosive or tend to break down athigh temperatures in the presence of the steam and free oxygen employedin the engines.

Many mineral oils, compounded heavy duty oils and synthetic oils havebeen extensively tested in an effort to eliminate this slick type ofwake While retaining the necessary high lubricity and anticorrosivecharacteristics required for use in the engines of the hydrogen peroxidetype. The results of these tests showed that to perform as required, alubricant must be either water soluble or have a specific gravityconsiderably greater than that of sea water. These characteristics mustbe retained even after the lubricant has been subjected to the rigors ofthe high temperatures developed in the combustion chamber of hydrogenperoxide engines or the like.

2,894,909. Patented July 14, 1959 Of the many oils tested only the watersoluble oils formed by the polymerization of alkylene oxides have beenfound to have characteristics which approach those found to be necessaryfor use under the above described conditions. These water solublepolymerized alkylene oxide oils have lubricity characteristics whichcompare favorably with conventional petroleum oils. They are superior tomost petroleum oils with regard to viscosity index, pour point andsludge formation. However, these alkylene oxide oils have been found togive inadequate lubrication under the conditions of operation describedfor the hydrogen peroxide engine and have been found to be undulycorrosive when compared to hydrocarbon oils.

Attempts to improve the lubricity and anticorrosive characteristics ofthe polymerized alkylene oxide oils while retaining their water soluble,slick free qualities have not heretofore been successful. All previouslyknown additives either do not improve the lubricity and anticorrosivecharacteristics of the oils or result in the lubricant forming thehighly undesirable slick.

It is therefore, an object of the present invention to provide a new andimproved additive for use with alkylene oxide oils.

Another object is to provide a new and improved alkylene oxidelubricating compound having improved lubricity and anticorrosivecharacteristics.

A further object is to provide a new and improved lubricatingcomposition which is soluble in water and will not form a slick whenused under water.

A still further object is to provide an additive for improving thelubricity characteristics of alkylene oxide oils while decreasing theircorrosiveness.

Other objects and the attendant advantages of the invention will beapparent to those skilled in the art as the invention is disclosed inthe following detailed description.

The objects of the present invention are achieved by the addition to thealkylene oxide oil of a small proportion of ammonium linoleate. Theaddition of as small a quantity of ammonium linoleate as l-2 percent byweight permits satisfactory lubrication of an internal combustion engineeven when 50 percent of sea water is present in the crankcase of theengine. The addition of this small proportion of ammonium linoleate alsopermits the use of the mixture as a steam cylinder lubricant.

The ammonium linoleate which is used in the invention has the formula NHC H CO and may be prepared by any of several well known methods such asthe ammonialysis of linoleic acid. Ammonium linoleate is commerciallyavailable and any reasonably pure product may be utilized in thecomposition of this invention.

The alkylene oxide oils used in the lubricating composition of theinvention are the oils composed of the water soluble polymerizedethylene glycols and derivatives thereof. These oils are commerciallyavailable under the trade name Ucon Lubricants from the Carbide andCarbon Chemicals Company. Only the water soluble oils are useful in thecomposition of this invention however. Ucon HB series lubricants arewater soluble oils made by copolymerizing a mixture of ethylene oxide (CH O) and propylene oxide (C l-I O). These oils, being water soluble,form no slick on the surface of water. They do not carbonize in theengine as badly as petroleum oils but are depolymerized forming watersoluble glycols, acids and aldehydes leaving an exceptionally cleanengine. These oils may be polymerized to any desired viscosity. Of theUcon HB series lubricants Ucon 50 HB 660 is the preferred lubricant.This oil is made by copolymerizing a 5050 mixture of ethylene oxide andpropylene oxide. As commercially available Ucon 50 HB-660 has thefollowing properties:

Viscosity, SSU at:

Mere mechanical mixing of the ammonium linoleate with the Ucon lubricantoil will allow some separation of the constituents after prolongedstanding at room temperature.

A permanent colloidal suspension of the ammonium linoleate may best beprepared by first mixing the ammonium linoleate with the oil dissolvingit in carbon tetrachloride and then adding this solution to the warmedoil with stirring. The carbon tetrachloride may then be removed bywarming the mixture.

The following example is given by way of illustration and is not to beconstrued as limiting the invention in any manner.

EXAMPLE I A mixture of Ucon 50 HB 660 and ammonium linoleate wasprepared by dissolving the ammonium linoleate paste in carbontetrachloride at 90 degrees F. This solution was added to the Ucon 50 HB660 at 135 degrees F and stirred for fifteen minutes. The carbontetrachloride was removed by heating the mixture to 200 degrees F. undera vacuum.

The test for the formation of an oil slick was performed on a onecylinder, four stroke cycle, Lauson gasoline engine so modified as togive a condition of excessive oil consumption. For this purpose the oilcontrol ring was removed from the piston leaving only the twocompression rings. A mixture of hydrogen, oxygen and steam was used asthe fuel. The exhaust from the engine was piped to the lowest point of atank holding 15 gallons of synthetic sea water about four feet deep. Abaflle plate with small holes was placed above the exhaust line todistribut the gases throughout the tank area.

Straight mineral oils and compounded heavy duty oils formedobjectionable oil slicks on the water surface with the above test.Various synthetic oils were also tested including glycerin, tricresylphosphate, Hydrolubes, Ucon LB series, Arochlor 1278, Gulf OECA and DowCorn ing Fluids #200, #710 and #500. All the oils tested gaveunsatisfactory results except the Ucon HB series. When Ucon 50 HB 660plus the ammonium linoleate was tested the entire products of theexhaust were soluble in the water and left no slick on the surface.

The mixture of Ucon 50 HB 660 and ammonium linoleate was tested forcomparison with other lubricants on a wear test machine. The testingmachine used to test the oils was a constant speed (1800 r.p.m.) motorwith a hardened steel wheel attached to the shaft. This wheel washardened to Rockwell 60c. The motor was attached to a base plate whichheld a lever arrangement that permitted loading of the test piece. Thetest pieces were cold rolled steel /2 x 2" x The loading wasaccomplished by using the lever arrangement to force the test pieceagainst the Wheel. A 5:1 lever ratio gave a 20 pound loading at thepoint of contact. The

tested lubricant was fed from a drip oiler so it just contacted the edgeof the wheel as it was fed.

The test was started by allowing the oil to completely cover the sampleand to flow at an arbitrary drip rate (about drops per minute) which wasmaintained for the duration of the run. The sample was allowed to comeinto contact with the wheel and the test was allowed to run for 5minutes. The test was secured by removing the sample from contact withthe wheel. The resultant length of the mark on the test sample servedasa comparative measurement of the quality of the lubricant tested.

A petroleum base oil SAE 30 blended with 20 percent of brown rape seedoil was used as a standard for comparison since this mixture of oils wasfound to permit engine operation in the presence of sea water, oxygenand steam as described above even though the lubricating qualities ofthe oil appeared to be marginal and it caused a bad oil slick.

For the purpose of the tests eachof the oil samples tested was dilutedwith an equivalent amount of .synthetic sea Water so as to produce alubricant containing 50 percent sea water.

Table I shows the averages obtained from a series of wear tests on theUcon 50 H13 660 without additive, on the Ucon 50 HB 660 plus 2% ammoniumlinoleate and on the standard petroleum base oil.

UCON 50 HB 660 plus 2% ammonium linoleate .1050

The results of the wear test showed that the Ucon 50 HB 660-ammoniumlinoleate mixture had better lubricating qualities than the standardpetroleum baseoil and showed a reduction of over 50 percent of wear overUcon 50 HB 660 without additive.

The Ucon 50 HB 660-ammonium linoleate mixture was subjected to a storagetest. The ammonium linoleate remained in suspension at 50 degrees F. andafter 6 months at degrees F.

The anticorrosive characteristics were found to be satisfactory. Theneutralization numbers i.e. the number of mg. of potassium hydroxiderequired to neutralize one gram of oil areas follows Originally 2wks.4wks. -6.wks.

From the foregoing it may be seen that there. has been provided asynthetic lubricant composition which has lubricative characteristicscomparable to or better than the best petroleum oils when mixed with upto 50 percent sea water and which is water solubleeven after beingsubjected to the high temperatures of the combustion chamber of vaninterenal combustion engine and which accordingly forms no undesirableslick on the water. This improved lubricating composition composed ofcopolymerized ethylene oxide and propylene oxide with up to 2% ammoniumlinoleate has been employed successfully with no corrosive results insubmarine and torpedo engines of the hydrogen peroxide type.

Obviously many modifications and variations of the present invention arepossible in the light of the above teachings. It is therefore to beunderstood that within the scope of the appended claims the inventionmay be practiced otherwise than asspecificallydescribed.

What isclaimedas new-and desired-to-be securedby Letters Patent of theUnited Statesis:

1. A water soluble lubricating compositioncomprising a water solublepolymerized alkylene oxide oil consisting of ethylene oxide andpropylene oxide, and substantially 2 percent by weight of ammoniumlinoleate.

2. A water soluble lubricating composition comprising I an alkyleneoxide oil containing substantially 50 percent by weight of polymerizedethylene oxide and 50 percent by weight of polymerized propylene oxide,and an additive consisting of substantially 2 percent by weight ofammonium linoleate.

3. A water soluble lubricating composition comprising a water solublealkylene oxide oil consisting substantially in a 1:1 ratio ofcopolymerized ethylene oxide and propylene oxide, and havingsubstantially 2 percent by weight of ammonium linoleate mixed therein.

References Cited in the file of this patent UNITED STATES PATENTS OTHERREFERENCES Ucon, Carbide and Carbon Chem. Corp., N.Y.

(1948), Table No. 3, between pages 10 and 11.

Ind. and Chem. Eng., vol. 40, No.

12, page 2346.

1. A WATER SOLUBLE LUBRICATING COMPOSITION COMPRISING A WATER SOLUBLEPOLYMERIZED ALKYLENE OXIDE OIL CONSISTING OF ETHYLENE OXIDE ANDPROPYLENE OXIDE, AND SUBSTANTAILLY 2 PERCENT BY WEIGHT OF AMMONIUMLINOLEATE.